Risk factors

While the exact cause of congenital heart defects, such as truncus arteriosus, is unknown, several factors may increase the risk of a baby being born with a heart condition. These include:

Viral illness during pregnancy. If a woman contracts rubella (German measles) or another viral illness during early pregnancy, the risk of congenital heart defects in her baby is increased.

Poorly controlled diabetes during pregnancy. Diabetes that isn't well-managed can increase the risk of birth defects, including heart defects.

Certain medications taken during pregnancy. Many medications aren't recommended for use during pregnancy because of potential risks to the fetus.

Certain chromosomal disorders. Children with DiGeorge's syndrome or velocardiofacial syndrome have an increased risk of truncus arteriosus. These conditions are caused by an extra or defective chromosome.

Smoking during pregnancy. Continuing to smoke while pregnant increases the risk that the baby will be born with a heart defect.

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